Typewriting machine having automatic cutoff switch



K. R. STAUSS Jan. 12, 1954 TYPEWRITING MACHINE HAVING AUTOMATIC ,CUTOFFSWITCH 2 Sheets-Sheecl l Filed Oct. 27, 1950 Jan. 12, 1954 K, R, sTAuss2,665,792

TYPEWRITING MACHINE HAVING AUTOMATIC CUTOFF SWITCH Filed Oct. 27, 1950 2Sheets-Sheet 2 L I r lNvENToR K. STA U55 ATTORNEY Patented Jan. 12, 1954TYPEWRITING MACHINE HAVING AUTO- MAT-IC GUTOFF SVJITCH Karl. R.v Stauss,Poughkeepsie, N. Y., assigner to International Business MachinesCorporation,

New YorkN. Y., a corporation of New York Application October 27, 1950,Serial No. 192,402

(Cl. 197-l7) 11 Claims.

This invention relates to typewriting machines.

The broad object of the present invention is to improve power operatedtypewriters.

An Objectis tol provide a means oi"` automatically Stopping the drivingmotor of a power operated typewriter if the machine remains unattended'for longer' than a predetermined period.

An object is to provide a simple and` reliable thermal cut-out switchforcontrolling the driving vmotor of a power operated typewriter.

An object is to provide a thermal cutout switch which the automaticswitch opening function is'Y combined with the manual control of theswitch 'to enable the machine to be started and stopped icy handindependently of the thermal control.

rllhe invention mainly consists in the provision of a combination ofthermo-responsive elements which becomel automatically effectivetointerrupt the circuit to the driving `motor when the machine is` leftYidle with the main switch closed for longer than. a predetermined time.

Other objects of the invention will be pointed out in the followingdescription and claims and illustrated in the accompanying drawings,which disclose, by way of example, the principle of the invention andthe best mode, which has been. contemplated, of applying that principle.

In the drawings:

Fig. 1 is a vertical section through a portion of a power operatedtypewriter embodying the presf ent invention.

Fig. 2 is a plan view of the contact mechanism which is responsive toactivity of the typewriter.

Fig. Sis a front elevation of the cutout switch.

Fig. 4 is a rear elevation of the cut-cut switch.

Fig. 5 is a right side elevation of the cut-out switch.

Fig.. 6 is a wiring diagram of the invention.

The invention is shown as applied to a power operated typwriting machineof the type disclosed in application Serial No. 7 52,7 23, nled June 5,1947, by Ronald D. Dodge and issued as U. S. Patent No. 2,506,444, May2, 1950. lt will be understood, however, that it is not limited tov themachine chosen for purposes of illustration of the invention, but may beapplied to other power operated typewriters equally as well.

In machines of the type disclosed in the aforementioned application,there is, provided a power roller le which is driven continually in thedirection of the arrow (Fig. l) by a suitable driving motor which in thepresent case is. shown diagrammatically in Fig. 6 and designatedCooperating with this power roller are power units .like the onedesignated il in Fig. 1 which are. con- 2 trolled by keys like l2. Thesekeys, when d epressed, render the power units l l operative bythe powerroller lo and each power unit E l is actuated in a clockwise directionabout the left-hand end of the fulcruin member i3 as a pivot. The powerunits l have extensions l la for actuating a universal bar l. on thecross rod l5 through; a link connection l. The universal bar M actuatesalever Il which is part of the mechanismy for` operating the ribbonvibrator. This mechanism is diclosed in application Serial No. 756,174,filed June 21, 1947, by Ronald D. Dodge and issued as U. S. Patent No.2,616,547, November 4, 1952.

In the present case, the ribbon vibrator mechanism is of interest onlyto the extent that the link it and lever l? are utilized as a means.; ofdisabling the automatic cut-out switch when there is activity on thetypewriter; that is, when' it is in use to write on work sheets. Theuniversal bar I4 is operated every time characters4 are printed by thetypewriter; consequently, the link I5 becomes stationary when activityat the machine ceases.

Associated with the lever I i is a contact mechanism best shown in Fig,2, which involves the movable spring Contact blade l2 having a strip-ofinsulating material i3d projecting into the plane of the lever ilwhereby the blade it is vibrated by the operation of the lever Ilthrough the` link l5, mentioned above. Coacting with the contact bladei8 is a xed contact blade i9 which, along with blade iii, isinsulatablyy mounted in the base of the machine and extends parallelwiththe blade i8' in Fig. 2. The blades 8 and I9 have cooperating contactsdesigna-ted Ci which are closed momentarily whenever the blade i8 isvibrated. Insulatably mounted between the two blades I8 and 3 is abimetallic contact blade 20 which bears one of two contacts designatedC2, the blade I il carrying the other contact C2. Surrounding thebimetaliic contact blade 2G is a heater Hl comprising a coil ofresistance wire which is designed to heat the bimetallicmember 2liV andcause it to bow in a countercloc'swise direction to open contacts C2.

The machine is provided with a switch lever 2l (Fig. 1) which is pivotedat 22a in the base 22 0f the machine and, in the position in Fig. 1, theswitch lever is in the Gir position.

The switch lever is provided with an arcuate indicator 2 la whichV hasthe words Od and On engraved or suitably marked thereon and the cabinetof the machine has a suitable aperture to display these words when theswitch lever 24 is set in the corresponding positions. Pivotallyconnected to the switch lever 2l is a link 23 which is connected to thecut-oli switch shown in Figs. 3, 4, and 5. In these views, the cut-offswitch is shown in the motor Off position. The link 23 is pivotallyconnected to the mid-point of a plate 24 of insulating material which ispivotally connected by means of studs 25a, 25a to brackets 25, 25carried by the lingers 2l, 28, respectively. These lingers are mountedon flexible strips 2S which in turn are insulatably mounted on a frame 3il by means of the screws 3 I.

It is clear that when the switch lever 2i is rocked clockwise (Fig. l)to the motor On position, the link 23 will be thrust to the left and theplates 2'! and 28 will be rocked counterclockwise (Fig. 3) or clockwise(Fig. 4) into a latching relation with the latches 32, 33.

The latches 32, 33 are pivotally mounted on a pin 30a carried by lugsformed in the frame 32 and are urged in a clockwise direction (Fig. 3)by the torsion springs 34 so as to snap over the ends of the lingers 2l,28 in the position to which they are moved by the switch lever 2i. Thelatches 32, 33 are formed with lugs 32a, 33a which limit rotation of thelatches under the influence of the springs 31%, and position the latchesas in Figs. 3 and 4 when the switch is either "On or O Cooperating withthe finger 2l are four spring Contact members bearing the contacts C3,C2, and three other contact members bearing the contacts C6, Clcooperate with the linger 23. The finger 2 has an insulating button 2idwhich is adapted to engage the right-hand member (Fig. 3) for thecontacts C3 to close said contacts when the switch lever 2i moves to theOn position. The nger 2S has a button 28a (Fig. 4) arranged to operatethe middle contact member for the contacts C5, C6, so as to close thecontacts C and open contacts CS when the switch lever 2l is placed in Onposition.

The latch 32 (Fig. 3) has secured to it a contact operating finger 32hwhich projects downwardly and holds the contacts Ce closed by pressingthe right-hand contact member therefor to the left. Under normalconditions, with the switch lever in the oli position, contacts C4 willbe closed but will be momentarily opened and reclosed when the latch 32is operative to latch the fingers 2l. The bracket 25 also has a pair offingers 25h which are formed so as to loosely project on each side ofthe linger 28 and the main part of bracket 26.

Each latch 32, 33 has a linger 32e, 33o (Figs. 3 and 4) engaged by abimetallic spring member 35a, 35h and coactng with each such springmember is a bimetallic member 35a, 35h each having a heater H2, in thecase of the latch 32, and H3, in the case of the latch 33. Thebimetallic members 35a, 36h are bent at their upper ends to bearcontacts C3 thereby starting the driving motor M in Fig. 6. Also, thecontacts C5 close and contacts C5 are opened by linger 28. rEhe closureof contacts C5 connects the heater H3 and contacts 4 C2 in a seriescircuit across the line wires and, if nothing else happens, the heaterH3 will start the bimetallic members 35h, 36h to bowing in acounterclockwise direction (Fig. 4)'thereby tending to graduallydisconnect the latch 33 from the end of finger 28. After a period oftime determined by the physical constants of the heater H3 and thebimetallic members 35h, 365, the latch 33 will release the linger 28which will spring part way to the position shown in Fig. 4 and will movethe pivoted point of the link 23 half way to the normal position.Fingers 25h limit this movement of finger 28. However, the nger 21 willremain latched by the latch 32 and contacts C3, C4 will remain closed.

The release of the finger' 2S allows the contacts C5 to reclose and C5to reopen thereby connecting the heater H2 in series with the contactsC2 and the heater H2 commences to heat. If the machine still remainsinactive, the latch 32 will be gradually disengaged and release finger2'! after a definite period of time dependent upon the physicalconstants of the heater H2 and the bimetallic elements 35a, 36a. Thisallows the contacts C3, C4 to open to stop the motor.

If the operator, after setting the switch 2l to On position, commencesto operate the machine to type on a work sheet, the operation of thetypewriter power units will cause the link l5 to be reciprocatedhorizontally so as to periodically open and close the contacts Cl. Thiswill cause the heater HI to be periodically impulsed with the currentwith the result that it causes the bi-metallic member 25 to bow in acounterclockwise di-f rection (Figs. 2 and 6) and open the contacts C2.-The opening of the contacts C2 disconnects the heaters H2, H3 and allowsthem to cool. Thus,v as long as the operater is using the machine, theheater HI will be kept hot enough to prevent the heaters H2, H3 fromfunctioning and the motor M will remain in circuit. If the operator nowgoes away and leaves the machine unattended, the heater HI will coolvery rapidly and allow the contacts C2 to reclose thereby reconnectingthe heaters H2, H3 in circuit. Since the motor M is running and themachine is active, the contacts Cri, C5 are normally closed, the heaterH3 will then again function to first open the contacts C5 and closecontacts C6 and then finally heater H2 will open contacts C3 to stop themotor as described above.

There is a possibility that due to faulty operation of the machine, thecontacts Ci may be left in a closed condition with the power on themachine. This often happens when several keys are operatedsimultaneously and the type bars jam in the type basket thereby stallingthe motor and the power roller I3. In order to get a long time interval,it is desirable that the heaters H2, H3 be relatively sluggish and ofhigh resistance so as to accumulate heat relatively slowly. It isdesirable that the time interval before power is cut oir from the motorbe long enough to allow the stenographer to perform small dutiesconnected with typing, such as arranging books, turning pages, oranswering the telephone.

On the other hand, it is desirable that the action of the heaters H2, H3be fairly quickly suspended as soon as the machine is put intooperation. For that reason it is desirable that the heater HI and theelement 22 be relatively quick acting which requires that the heater Hlbe of low resistance so as to permit the relatively heavy currentnecessary to quickly heat the bi-metallic member 20. If the heater HIhas these characteristics. it: will be: damaged it.y is kept# coninectedacross. the? line' wiresl for any great length of. time which, ofcourse', would be` the: case if' the contacts Cl were held' inv closedcondition as by a jaml of the" type bars hr the: basket.

It will: be` noted in. 2` that the. bladey I8 is considerably longerthan the' clade Irs and the plate 18a' also increases itsv eiilective.length.. relaitive to the lever' t't so that. the blader l-Slf willy becapablev of flexing tof permit the bowing thereof to theY right.- (Fig.21)l to oper-i2 thet contacts. Ct. The member l@ isprovided. witlr anxinsulating button IS-b which is engaged' by the bi-metallic member 2.0-when the latter is excessively heated and causes the member lil to' iiexsudcientlyf to openl the contacts Cl thus disconnecting. the heaterH-lfrom the line. Of course,Y asV soon: as the heater HI isdisconnected, it. willstart to` cool and' theV4 bi-metallic member '2liwillpermit the contacts CI- toreolose, whereupon the hea-ter H andmember will again hccomeeirective to flex the member i3. Thus, theheater Hl will be impulsed at intervals whichv will be very short owingto the fact that. the heater Hl and loi-metallic member -re essentiallyquiet: acting, but theinterva-ls when the circuit is open will. be longenough to prevent overheating the heater Ht.

While there have beenV shownv and describediand pointed out the.funda-mental novel features of the invention as applied tol a preierredembodiment, it willbe understood that various omissions andsubstitutions and changes in the form and details of the deviceillustrated and in its operation may be made by those skilled in the artwithout departing from vthe spi-rit or" the inventi-on. I-t istheintention', therefore, to he limited only as indicated by the scope ofthe following claims.

What is claimed is:

1. In combination with a power operated office machine having a drivingmotor a control4 circuit for such motor, a main switch for controllingsaid motor circuit, a second. switch', manual. means to close saidswitches, means to hold said. switches in` closed condition, thermalmeans tendingv when heated to release the holding.. means, heatingmeansfor aid. thermal, means, a cut-o control circuit including said.heating means and second switch and a thermally released switch, andmeans responsive to use of said machine Jfor periodically energizing.said thermally released switch to maintain said cntoii control circuitopen.

2. In combination with a power operated of fice machine having a maindriving motor, a control circuit for said motor, a main switch forstarting and stopping said motor, and manual means to close said switch;means for maintaining said switch in closed condition, a thermal releasedevice for said maintaining means including a heater, a second switch incircuit with said heater and opened by the manual means when closing themain switch, means for holding said second switch in open position, asecond thermal release device for said holding means including a secondheater, a control circuit for said heaters arranged to include saidsecond heater when the main switch is closed and the nrst heater whenthe second switch is closed and including a thermally actuated heatercontrol switch for opening said circuit, a control heater for operatingsaid heater control switch, and contact means actuated by activity ofsaid cnice machine for closing a circuit to the control heater.

3., Inlcombinatinn with. a: power operated office machine having az.power circuit, al switch: for closing said circuit and manual means forloperating: the main switch, releasable means to hold: themain switchclosed, a first thermal device for releasing the holding. means', afirst heater. for the: rst thermal device, a second switch actuated bysaid manual means to an oper ated position. andr comprising transfercontacts arranged; toclosea circuit; totl said'. lirst heater when.released, a; second holding means for hold.- ing. the second switch inoperated position and having. a.. second heater toi-winch av circuit. isclosed by the secondi switch. in; its. operated position,v a thirdswitchi, a control'. circuit. including said heaters and. said' thirdswitch in a seriesy parallel arrangement, and means controlled by'activity of said office machine: for Inaintainingv the third switc-:lr:Vin open position to prevent heating either oi said; heaters while said;machine is. inf use.

4. In combination with: a power operated office machine: having. al mainpower circuit, main switch for' closing said circuit and manuali meansfor operating. the main switch, releasable: means to: hold the mainrswitch closed, a first thermal device for releasing the holding means, arst heater.vv for the nrst thermal device. a second switch actuated-L bysaid; manual means to. an operated position and comprising transfercontacts arranged to close. a. circuit to.- said. first. heater whenvreleased, a secondi holding means for holding! the secondI switch irrits operated position and having a second heaterto: which a circuit isclosed' by the second switch in its opera-ted position, a third switch,.a. control circuit including said heaters and said third switch in aseries parallel arrangement, and' a thermal device. for

opening the thirdv switch including athird heater and means responsiveto activity of said machine forl periodically closing a circuit; to thethird heater to maintain the third switch in open position and preventheating either of saidy iirst and second heaters while said machine isin use.

5. In combination with an oilice machine having. a main power circuitand a part which operates at closely' spaced intervals when the machineis in use, a main heater control circuit, a series of three thermallyreleased switches each having aheater for releasing the associatedswitch, the first of said switches being disposed in said main powercircuit and constituting a main power switch, the second of saidswitches being closed when the main power switch is closed and operativeto connect the heater for said second switch in said circuit and.disconnect the heater for said main power switch` from said circuit torender thev second heater effective to release the second switch, said`second switch being effective when reelasd to connect the heater for themain power switch in said circuit to effect release of said main powerswitch, said main power switch being operative when released to opensaid main power circuit, the third switch being operative to open saidheater control circuit, and means for closing a circuit to the heaterfor the third switch under control of said active element when themachine is in use.

6. In an oiiice machine having a main power circuit and a part which isactive at closely spaced intervals while the machine is in use, a heatercontrol circuit, a pair of thermally released switches each having aheater for releasing the associated switch, one of said switches whenset connecting its heater in said control circuit and when releasedconnecting the other heater in said control circuit, the second switchwhen set closi ing said power circuit and when released opening saidpower circuit; means to simultaneously set said switches, a thermallyactuated switch in said heater control circuit and having a heater foroperating the switch to open position, and a circuit for the last namedheater including a switch actuated by said active part.

7. In an oice machine having a main power circuit and a part active atclosely spaced intern vals when the machine is in use, a heater ccntrolcircuit, a pair of switches each having a latch for holding the switchin a set condition, each latch having thermal release means and a heaterfor the thermal release means, one of said switches when set connectingits heater in said control circuit and when released connecting theother heater in said control circuit, the second switch when set closingsaid power circuit and when released opening said power circuit; meansto simultaneously set said switches, a thermally actuated switch in saidheater control circuit and having a heater for operating such switch toopen position, and a circuit for the last-named heater including aswitch actuated by said active part.

8. In combination with a power operated oice machine having a motorcircuit, a main power switch for controlling said motor circuit, asecond switch, manual means to close said switches, latch means to holdsaid switches in closed condition, thermal means tending when heated torelease the latch means, heating means for said y thermal means, acut-oir control circuit includ ing said heating means and second switchand a thermally released switch, and means responsive to use of saidmachine for periodically energizing said thermally released switch tomaintain said cut-off control circuit open.

9. In combination with a power operated oce machine having a maindriving motor, a control circuit for said motor, a main switch forstarting and stopping said motor, and manual means to close said switch;a first latch for maintaining said switch in closed condition, a thermalrelease device for said iirst latch including a heater for releasing thelatch, a second switch in circuit with said heater and opened by themanual means when closing the main switch, a second latch for holdingsaid second switch in open position, a second thermal release device forsaid second latch including a second heater, a control circuit for saidheaters arranged to include said second heater when the main switch isclosed and the rst heater when the second switch is closed and includinga thermally actuated heater control switch for opening said circuit, acontrol heater for operating said heater control switch, and contactvmeans actuated by activity of said oice machine for repeatedly closinga circuit to the control heater.

10. In combination with a power operated oiilce machine having a mainpower circuit, a rst switch for closing said circuit and manual meansfor closing said switch, releasable means to hold the rst switch closed,a irst thermal device for releasing the holding means, a first heaterfor the rst thermal device, a second switch comprising transfer contactsarranged to close a circuit to said rst heater when released andactuated by said manual means to an operated position, a second holdingmeans for retaining the second switch in operated position, a secondthermal device for releasing the second holding means, a second heaterto which a circuit is closed by the second switch in its operatedposition for heating the second thermal device, a control circuitincluding said heaters and said second switch in a series parallelarrangement and a thermally actuated switch having a third heater, andmeans controlled by activity of said oice machine for repeatedly closinga circuit to the third heater to maintain the thermally actuated switchin open position to prevent heating either of the rst two heaters whilesaid machine is in use. l

11. In combination with an ofce machine having a main power circuit anda part which operates at closely spaced intervals when the machine is inuse, a main heater control circuit, a series of three thermally releasedswitches each having a heater for releasing the associated switch, therst of said switches being disposed in said main power circuit andconstituting a main power switch, the second of said switches beingclosed when the main power switch is closed and operative to connect theheater for said second switch in said circuit and disconnect the heaterfor said main power switch from said circuit to render the second heatereiective to release the second switch, said second switch beingeffective when released to connect the heater or the main power switchin said circuit to effect release of said main power switch, said mainpower switch being operative when released to open said main powercircuit, the third switch being operative to open said heater controlcircuit, and contact means for repeatedly closing a circuit to theheater for the third switch under control of said active element whenthe machine is in use.

KARL R. 'sTAUss References Cited in the ille of this patent UNITEDSTATES PATENTS Number

